(1) Field of the Invention
This invention generally relates to a torpedo tube test plug. More particularly, this invention is intended to eliminate the need for a conventional or known submarine torpedo tube test plug, thereby eliminating the cost for the plug, and to simplify the procedure for pressure testing a torpedo tube.
(2) Description of the Prior Art
Existing torpedo tube test plugs are substantially similar to that shown in FIGS. 1 through 8 of the present application by way of example only. In particular, a breech door at a breech end (not shown) of a torpedo tube barrel 10 and all of the torpedo tube mechanisms are subjected to sea pressure from within the torpedo tube 10 under normal operating conditions.
However, as particularly shown in FIGS. 3 and 6, a muzzle door 16 at a muzzle end 22 of the torpedo tube 10 is only subjected to pressure when it is closed and an ambient sea pressure is greater than a pressure within the torpedo tube barrel 10. This excessive pressure condition occurs whenever the torpedo tube breech door (not shown) is open, the torpedo tube 10 is not flooded, the torpedo tube 10 is flooded but not pressure equalized, or the ship is diving faster than the pressure equalization system can keep up with the increase in sea pressure. Therefore, the conventional muzzle door 16 is designed to withstand pressure from the sea rather than from inside of the torpedo tube 10.
For this reason, a muzzle door gasket 18 is known to be designed and provided in connection with the muzzle door 16 so that an increase in depth will improve the sealing capabilities of the muzzle door 16; however, the torpedo tube muzzle door mechanism with a hydraulic power cylinder has insufficient power or force to hold the muzzle door 16 closed with high internal pressure.
FIGS. 1 and 2, in particular, reflect an initial known configuration for a torpedo tube test plug 20. The torpedo tube test plug 20 is used to plug the muzzle end 22 of the torpedo tube 10 when it is necessary to pressurize the torpedo tube 10 to validate its strength or tightness.
In operation, the muzzle door 16 of the torpedo tube barrel 10 is opened and the torpedo tube test plug 20 is slid into the muzzle end 22 of the torpedo tube barrel 10. The test plug 20 has a seal 24 which seals against an interior surface of the torpedo tube 10. A circular segmented key 26 having at least four segments 26a, 26b, 26cand 26d is then placed into a keyway 28 in the torpedo tube 10 and each segment 26a, 26b, 26c, and 26d is bolted to the test plug 20. As shown, a plurality of bolt apertures 12 are provided through which corresponding bolts 14 are inserted for securing the segments 26a, 26b, 26c, and 26d to the test plug 20. Finally, a special guide slot plug 30 is installed to seal a guide stud slot 32.
This configuration has been very effective for its intended purpose and has been used for many years. Some disadvantages do exist, however, including that the test plug 20 can only be installed when a ship is in drydock. Another disadvantage is that the manufacturing, storage, installation and removal, all add considerably to the cost associated with high pressure testing of a torpedo tube 10.
When the SSN 21 Class was being developed, it was decided to overcome the disadvantage associated with the necessity to drydock a ship for installation of a test plug. FIGS. 3 through 6 reflect the testing configurations which were developed thereafter.
In this configuration, referring to FIGS. 3 and 4, the muzzle door 16 is actually used to seal the muzzle end 22 of the torpedo tube. However, in order to prevent the muzzle door 16 from lifting off its seat when pressure is applied to the inside of the torpedo tube 10, sixteen pie shaped segments 34 are keyed into the torpedo tube barrel 10 and bolted with a plurality of bolts 36 directly into the muzzle door 16. When pressure is applied to the inside of the muzzle door 16, the pie shaped segments 34 pull attachment bolts 36 such that a pointed end 38 of the segments tend to cantilever toward the center 40 of the door 16. This bending of the pie shaped segments 34 at the pointed end 38 thereof, could produce high stresses in the torpedo tube keyway 28. In order to counteract this situation, a center support cylinder 42 is placed in the center 40 of the door 16 to prevent the segments 34 from bending and producing the high stress area.
This fixture eliminates the need for a separate test plug and may be installed while the ship is waterborne. However, some disadvantages remain, including that torpedo tube lands 44 and 46 have to be removed in order to install the sixteen segments 34. These lands 44 and 46 are bolted and pinned to the inside of the torpedo tube barrel 10 and their removal and re-installation is a substantial undertaking. In addition, once the lands 44 and 46 are removed, the installation of the sixteen segments 36 is difficult and time consuming as the installer has to lay in the torpedo tube barrel while lifting, positioning and bolting rather heavy pieces in locations which are awkward to access.
With the development of the New Attack Submarine it was decided that it was still desirable to pressure test a torpedo tube while the ship was waterborne, but a clamping system was desired which would not require the removal of the torpedo tube lands 44 and 46.
The clamping mechanism designed for the New Attack submarine is reflected by FIGS. 5-8. In this configuration, four fixtures 48a, 48b, 48c, and 48d are manufactured so that they fit between the torpedo tube lands 44 and 46 and are keyed into the keyway 28 in the torpedo tube barrel. Each fixture 48a, 48b, 48c, and 48d is held in place by fasteners 50 which hold the respective fixture to the barrel 10. Once the fixtures 48 are held to the barrel 10, four bolts 52 are threaded into the muzzle door 16. The design is a significant improvement over the previous design but it still requires the installation of a plurality of bolts 50 and 52 and four rather large and heavy segments 48 in an extremely cramped working space. In addition, the fasteners and segments must be stored and then carried through the length of the torpedo tube 10 to their installation location.
None of the prior art teaches or suggests a torpedo tube test plug as disclosed in the present application which can be easily installed while the submarine is waterborne.